Technical Field
[0001] The present invention relates generally to the field of mobility in wireless communication
systems. More particularly, it relates to mobility in systems applying signal beam-forming.
Background
[0002] In a typical cellular communication system, it is important to enable handover functionality.
Handover is the process of transferring control over an ongoing connection between
a (mobile) wireless communication device and the network providing the cellular communication
system from one network node (the serving network node, providing a serving cell)
to another network node (the target network node, providing a target cell). Handover
is typically provided to accomplish a transparent service for the wireless communication
device over a geographical area which extends beyond the coverage area of a single
network node. Preferably, a handover should be performed without any (or with minimal)
loss of data and without any (or with minimal) interruption in the communication of
the ongoing connection.
[0003] Enabling of handover functionality typically comprises finding of a suitable target
cell and ensuring (or making probable) that it is possible to sustain reliable communication
with the found suitable target cell.
[0004] Candidate cells (provided by candidate network nodes) for finding of the suitable
target cell are typically stored in neighbor lists, which may be stored at the serving
network node or elsewhere in (or in association with) the network providing cellular
communication system, as suitable.
[0005] To evaluate whether it is possible to sustain reliable communication with any of
the candidate cells, the quality of a possible connection between the wireless communication
device and the candidate cell are typically estimated before a decision to perform
a handover takes place. Such estimation may typically be done based on downlink measurements
carried out by the wireless communication device on reference signals transmitted
by the candidate cells and reported to the serving network node.
[0006] In many typical cellular communication systems, each network node continuously transmits
reference signals (e.g. pilot signals) that wireless communication devices in neighbor
cells may use to estimate the quality of a possible connection with the network node.
Examples of such reference signals comprise BCCH (broadcast control channel) in GSM
(Global System for Mobile communication), CPICH (common pilot channel) in UMTS (Universal
Mobile Telecommunication System), CRS (cell specific reference signal) in UMTS-LTE
(UMTS, Long Term Evolution) and beacon signals in the IEEE (Institute of Electrical
and Electronics Engineers) 802.11 standards.
[0007] Many emerging cellular communication systems may use advanced antenna systems to
enable communication in narrow beams directed from the serving network node towards
the wireless communication device, so-called beam-forming. Beam-forming may be used
to enable high signal strength in the direction of the beam while the interference
caused in other directions is kept low. Another advantage of beam-forming is that
coverage of a network node may be increased.
[0008] In systems employing beam-forming, there is typically a need for a beam switch functionality,
typically including switches between beams supported by the same network node as well
as switches between beams supported by different network nodes (i.e. handover). In
analogy with the established handover terminology, the beam before a beam switch is
called the serving beam and the beam that will be used after the beam switch is called
the target beam.
[0009] Throughout this disclosure, the term beam switch will be used to cover both the case
where the serving beam and the target beam are supported by the same network node
(i.e. when the beam switch does not involve a handover between network nodes, an intra-node
beam switch) and the case where the serving beam and the target beam are supported
by different network nodes (i.e. when the beam switch involves a handover between
network nodes, an inter-node beam switch).
[0010] Transmitting reference signals in all beams continuously to enable measurements for
beam switch decisions is not particularly efficient when a beam-forming system has
a large number of narrow of beams. One reason is that, in some typical scenarios,
only a few (or no) beams supported by a network node are active (e.g. used for a connection
with a wireless communication device) and transmitting reference signals in the rest
of the beams would only consume power, add interference and require extra hardware
resources.
[0011] An alternative approach is to have only a subset of candidate beams transmitting
reference signals, and only when it is probable that a beam switch (with or without
a handover) is needed. Such reference signals may be termed mobility reference signals
(MRS) and may, for example, have a similar physical structure to a secondary synchronization
signal (SSS) as defined in UMTS-LTE or any other suitable signal structure.
[0012] To determine when it is probable that a beam switch is needed, the serving network
node may use uplink measurements (typically making some assumptions regarding reciprocity)
and/or channel quality reports from the wireless communication device regarding the
connection. When the serving node determines that it is probable that a beam switch
is needed it may trigger a mobility procedure, where the candidate beams transmit
reference signals and the wireless communication device can perform and report measurements
of the reference signals to the serving network node for the beam switch decision.
The serving network node may inform the wireless communication device about the timing
(e.g. start and/or end) and/or content (e.g. signal sequences) of the reference signals
in association with triggering the mobility procedure.
[0013] Which beams to use as candidate beams may, for example, be based on content of a
database (e.g. a mobility look-up table, LuT). Such a database may (in analogy with
the neighbor cell list) comprise information regarding candidate beams for each serving
beam and/or for each geographical location of the wireless communication device. The
database may be formed and/or up-dated in any suitable way. For example, it may be
based on system set-up parameters and/or on statistics regarding previous beam switches
and/or measurements. The candidate beams for a serving beam may, for example, comprise
beams that have been used before and/or after a beam switch to/from the serving beam,
beams that have been associated with strong reference signal measurements for the
serving beam, and/or beams adjacent to the serving beam and supported by the serving
network node. The candidate beams for a geographical position may, for example, comprise
beams that have been associated with strong reference signal measurements for the
geographical position, and/or any combination with information regarding serving beam.
The database may, additionally, comprise (average) signal levels of the reference
signals for some of the candidate beams (e.g. the strongest) based on earlier measurements
for each serving beam and/or geographical position.
[0014] One problem with beam-forming systems (especially systems with narrow beams) is that
in some situations, the signal power (and typically the signal-to-interference ratio)
may decrease a lot during a very short time span. This time span may be so short that
there is not enough time to determine that it is probable that a beam switch is needed,
to trigger a mobility procedure and to complete a beam switch. Thus, the connection
between the wireless communication device and the network may be lost (e.g. due to
out-of-sync and subsequent radio link failure).
[0015] Figure 1 illustrates an example scenario where a sudden drop of the signal strength
may be experienced such that there is not enough time to prepare for and carry out
a beam switch as needed.
[0016] In Figure 1, a wireless communication device has an ongoing connection with network
node 120 via beam 110 when the wireless communication device is in position 100a.
When the wireless communication device moves around a corner of a building 130 it
ends up in a new position 100b where signals of the beam 110 cannot reach it (or reaches
it with a very low signal level) due to shadowing by the building 130. Furthermore,
interfering beams 111 (from network node 120, reflected of the building 131) and 112
(from network node 121) may be received at high signal levels by the wireless communication
device in position 100b, which results in a low signal-to-interference ratio.
[0017] Since the process of moving around the corner may be fast, the signal power of beam
110 (and the signal-to-interference ratio) may drop very quickly and the connection
between the wireless communication device and the network may be lost as explained
above.
[0018] Thus, there is a need for improved (or at least alternative) approaches to mobility
in cellular communication systems employing beam-forming.
[0019] WO 2015/08645 A1 discloses embodiments that relate to a network node and method performed by a network
node for controlling one or more Transmission Points (TPs) which transmit TP beams.
The network node selects a set of TP beams based on at least one of: one or more measurements
by the wireless device on first beam- specific reference signals of the TP beams and
a measured transmission from the wireless device. Each beam in a TP uses one unique
signal. The network node configures the wireless device with a set of second beam-specific
reference signals. Each second beam-specific signal is associated with a selected
TP beam. The node receives a report from the wireless device, comprising channel state
information for at least a subset of the selected set of TP beams, measured on the
set of second beam-specific signals.
US 2009/298502 A1 discloses aspects of handover, which is a main function that is used to support mobility
in the network. In a cellular communication network having adaptive antennas for enabling
narrow beam operation, it is assumed that a mobile unit is served by an active cell
set. Prior to establishment of a new serving radio link for a mobile unit, a narrow
target beam within a neighbor area of the current active cell set of the mobile unit
based on pre-established information of narrow beams within the neighbor area, and
establishment of the new serving radio link directly with the selected narrow target
beam is initiated. In this way, the narrow target beam can be selected at handover
initiation and the new radio link can be established directly with a target narrow
beam without first establishing the radio link with a cell-wide beam and then, after
uplink measurements, reconfiguring the radio link onto a narrow beam.
[0020] WO 2014/116928 A1 discloses a method and apparatus for determining a vertical beam for reception. A
method in a wireless transmit/receive unit (WTRU) includes receiving a broadcast message
from an evolved Node B (eNB) that includes information associated with a plurality
of vertical beams, wherein the information includes at least one set of Physical Random
Access Control Channel (PRACH) resources associated with each of the plurality of
vertical beams, measuring reference signals transmitted on each of the plurality of
vertical beams to select a reception vertical beam, transmitting a PRACH preamble
in a set of resources associated with the selected reception vertical beam, and receiving
communications from the eNB using the selected reception vertical beam.
[0021] US 2013/121185 A1 discloses a base station and mobile station that are configured to perform control
beam association. A method at the base station includes transmitting at least one
first control beam including reference signals on which the mobile station can perform
a measurement. The method also includes receiving a first measurement report from
the mobile station of the at least one first control beam. The method further includes,
based on the first measurement report, selecting at least one of the at least one
first control beam for at least one control channel for the mobile station to associate
with. The method still further includes transmitting control information in the at
least one control channel to the mobile station using the at least one selected control
beam, the control information comprising at least one resource allocation indication
for the mobile station. The at least one selected control beam is associated to the
mobile station.
Summary
[0022] It should be emphasized that the term "comprises/comprising" when used in this specification
is taken to specify the presence of stated features, integers, steps, or components,
but does not preclude the presence or addition of one or more other features, integers,
steps, components, or groups thereof.
[0023] The inventors have realized that the measurement report may be transmitted by the
wireless communication device and received by the network using a beam other than
the serving beam to lower the risk of losing the connection between the wireless communication
device and the network.
[0024] According to a first aspect, this is enabled by a method for a network node of a
cellular communication network. The network node and at least some other network nodes
of the cellular communication network are each adapted to support a plurality of beams
of a signal beam-forming scheme and to communicate with a wireless communication device
using at least one of the plurality of beams (the serving beam(s)).
[0025] The method comprises identifying one or more candidate beams and causing transmission
of a reference signal on each of the candidate beams.
[0026] The method also comprises causing reservation of an uplink resource of at least one
of the candidate beams (wherein the uplink resources are for conveying a report from
the wireless communication device, and wherein the report is indicative of a result
of measurements of the reference signals) and causing the communication with the wireless
communication device to use a target beam, wherein one of the candidate beams is selected
as the target beam based on the conveyed report.
[0027] The signal beam-forming scheme may, for example, be a MIMO (multiple-input, multiple-output)
scheme, a massive-MIMO scheme, or any beam-forming scheme employing narrow beams.
A beam-forming scheme employing narrow beams may, for example, be defined as a beam-forming
scheme where a network node supports at least 50, 100 or 200 beams in different directions.
[0028] The case where network nodes of the cellular communication network are each adapted
to support a plurality of beams of a signal beam-forming scheme and to communicate
with a wireless communication device using at least one of the plurality of beams
is used as a non-limiting example in this disclosure.
[0029] Communication with the wireless communication device using at least one of the plurality
of beams may comprise using one or more of the plurality of beams. In this disclosure,
the case where communication with the wireless communication device uses one of the
plurality of beams is used as a non-limiting example.
[0030] The identification of the candidate beams may, for example, be accomplished using
the database described in the background section.
[0031] Reservation of an uplink resource of at least one of the candidate beams may comprise
reservation of an uplink resource of each of the candidate beams. More generally,
reservation of an uplink resource of at least one of the candidate beams may comprise
reservation of an uplink resource of a number of the candidate beams, wherein the
number is any number between one and the number of identified candidate beams. In
this disclosure, the case where reservation of an uplink resource of each of the candidate
beams is used as a non-limiting example.
[0032] Causing the communication with the wireless communication device to use a target
beam may comprise causing a beam switch (which may or may not include a handover to
another network node). The beam switch (possibly including a handover) may be controlled
by the network node supporting the serving beam, or it may be controlled by a network
node supporting the target beam, or (in a more general case) by a network node supporting
any of the candidate beams.
[0033] The selection of one of the candidate beams as the target beam may be performed by
the network node supporting the serving beam, or it may be performed by a network
node supporting the target beam, or (in a more general case) by a network node supporting
any of the candidate beams (typically the network node receiving the report from the
wireless communication device).
[0034] In some embodiments, the method may further comprise detecting a decreasing signal
quality. A decreasing signal quality may be detected in any suitable way, for example,
via uplink measurements (e.g. decreasing signal-to-interference ratio or signal-to-interference
ratio being below a threshold) or via channel quality reports (e.g. channel quality
indication - CQI - or channel state information - CSI) from the wireless communication
device.
[0035] Additionally or alternatively, the method may, according to some embodiments, further
comprise detecting a signal environment statistics of a location of the wireless communication
device indicating that a signal-to-interference ratio of the location is below a signal-to-interference
ratio threshold. The statistics may, for example, be acquired using the database described
in the background section.
[0036] Additionally or alternatively, the method may, according to some embodiments, further
comprise detecting a failure of a mobility procedure. Detecting a failure of the mobility
procedure may, for example, comprise detecting absence of an expected signal (e.g.
a message or acknowledgement message of the mobility procedure), detecting out-of-sync
or detecting radio link failure.
[0037] At least the causing of reservation of uplink resources may, according to some embodiments,
be performed in response to detecting either or any combination of (as applicable)
the decreased signal quality, the signal environment statistics indicating the signal-to-interference
ratio being below the signal-to-interference ratio threshold, and the failure of the
mobility procedure. In some embodiments, either or both of identifying one or more
candidate beams and causing transmission of a reference signal on each of the candidate
beams may also be performed in response there to.
[0038] In some embodiments, the method may further comprise causing transmission of an indication
regarding the reservation of uplink resources to the wireless communication device.
[0039] In some embodiments, the indication regarding the reservation of uplink resources
is (implicitly) provided to the wireless communication device via transmission of
the reference signals. In some of these embodiments, transmission of a reference signal
is only done if a suitable uplink resource for conveying the report has been done.
[0040] In some examples, the reference signals may be structured into groups where the group
identity implies to which network node the report should be conveyed.
[0041] According to some embodiments, the selection of one of the candidate beams as the
target beam comprises selection of the one of the candidate beams on which the report
is conveyed in the reserved uplink resource.
[0042] For a candidate beam supported by the network node, causing transmission of the reference
signal on the candidate beam may comprise transmitting the reference signal and causing
reservation of the uplink resource on the candidate beams may comprise reserving the
uplink resource.
[0043] For a candidate beam supported by an other, candidate beam supporting, network node,
causing transmission of the reference signal on the candidate beam may comprise transmitting
a reference signal request to the candidate beam supporting network node and causing
reservation of the uplink resource on the candidate beams may comprise transmitting
an uplink resource request to the candidate beam supporting network node.
[0044] In some embodiments, causing the communication with the wireless communication device
to use a target beam comprises causing transmission of a beam switch command to the
wireless communication device.
[0045] Causing transmission of a beam switch command to the wireless communication device
may, for example, comprise transmitting the beam switch command to the wireless communication
device (e.g. if the target beam is supported by the network node).
[0046] If the target beam is supported by an other, target beam supporting, network node,
causing transmission of a beam switch command to the wireless communication device
may, for example, comprise performing a handover of the wireless communication device
to the target beam supporting network node.
[0047] Performing a handover of the wireless communication device to the target beam supporting
network node may, according to some embodiments, comprise causing the target beam
supporting network node to transmit a handover command to the wireless communication
device. The handover command may be a beam switch command in that it may comprise
an indication of which beam is the target beam.
[0048] A second aspect is a method for a wireless communication device adapted to communicate
with a network node of a cellular communication network, wherein the network node
and at least some other network nodes of the cellular communication network are each
adapted to support a plurality of beams of a signal beam-forming scheme and to communicate
with the wireless communication device using at least one of the plurality of beams.
[0049] The method comprises performing measurements of reference signals received on each
of one or more identified candidate beams (wherein at least one of the one or more
identified candidate beams has a reserved uplink resource for conveying a report from
the wireless communication device) and transmitting the report in one of the reserved
uplink resources, wherein the report is indicative of a result of the measurements,
wherein the report is for selection of one of the candidate beams as a target beam,
and wherein the target beam is for use in communication with the cellular communication
network.
[0050] In some embodiments, the report is transmitted in a reserved uplink resource of a
candidate beam, which is an other beam than the serving beam.
[0051] The reference signals may, additionally, be used to determine synchronization and/or
timing of the transmission of the report according to some embodiments.
[0052] In some embodiments, the method of the second aspect is performed by the wireless
communication device in association with the network node performing the method according
to the first aspect.
[0053] In some embodiments, the method of the second aspect comprises receiving an indication
regarding the reservation of uplink resources from the cellular communication network.
[0054] In some embodiments, the method of the second aspect comprises receiving information
regarding the reference signals (e.g. timing and/or content) from the cellular communication
network and performing the measurements in response there to.
[0055] In some embodiments, the method of the second aspect comprises detecting a failure
of a mobility procedure. Detecting a failure of the mobility procedure may, for example,
comprise detecting absence of an expected signal (e.g. a message or acknowledgement
message of the mobility procedure), detecting out-of-sync or detecting radio link
failure. The measurements may be performed in response to such detection (either blindly
with regard to the reference signals of the candidate beams or based on a most recent
information regarding the reference signals of the candidate beams).
[0056] The report may, according to some embodiments, be transmitted in the reserved uplink
resource of a candidate beam to be selected as the target beam.
[0057] The method may, according to some embodiments, comprise receiving a beam switch command
from the cellular communication network. In some embodiments, the beam switch command
may comprise a handover command (if the target beam is supported by a network node
other than the serving beam supporting network node, i.e. a target beam supporting
network node).
[0058] A third aspect is a computer program product comprising a computer readable medium,
having thereon a computer program comprising program instructions. The computer program
is loadable into a data-processing unit and adapted to cause execution of the method
according to any of the first and second aspect when the computer program is run by
the data-processing unit.
[0059] A fourth aspect is an arrangement for a network node of a cellular communication
network, wherein the network node and at least some other network nodes of the cellular
communication network are each adapted to support a plurality of beams of a signal
beam-forming scheme and to communicate with a wireless communication device using
at least one of the plurality of beams.
[0060] The arrangement comprises a controller adapted to cause identification of one or
more candidate beams, transmission of a reference signal on each of the candidate
beams, reservation of an uplink resource of at least one of the candidate beams (wherein
the uplink resources is for conveying a report from the wireless communication device,
and wherein the report is indicative of a result of measurements of the reference
signals) and the communication with the wireless communication device to use a target
beam (wherein one of the candidate beams is selected as the target beam based on the
conveyed report).
[0061] The fourth aspect may additionally have features identical with or corresponding
to any of the various features as explained above for the first aspect.
[0062] A fifth aspect is a network node of a cellular communication network comprising the
arrangement according to the fourth aspect.
[0063] A sixth aspect is an arrangement for a wireless communication device adapted to communicate
with a network node of a cellular communication network, wherein the network node
and at least some other network nodes of the cellular communication network are each
adapted to support a plurality of beams of a signal beam-forming scheme and to communicate
with the wireless communication device using at least one of the plurality of beams.
[0064] The arrangement comprises a controller adapted to cause performing of measurements
of reference signals received on each of one or more identified candidate beams (wherein
at least one of the one or more identified candidate beams has a reserved uplink resource
for conveying a report from the wireless communication device) and transmission of
the report in one of the reserved uplink resources, wherein the report is indicative
of a result of the measurements (wherein the report is for selection of one of the
candidate beams as a target beam, and wherein the target beam is for use in communication
with the cellular communication network).
[0065] The sixth aspect may additionally have features identical with or corresponding to
any of the various features as explained above for the second aspect.
[0066] A seventh aspect is a wireless communication device comprising the arrangement according
to the sixth aspect.
[0067] An eighth aspect is a method for a network node of a cellular communication network.
The network node and at least some other network nodes of the cellular communication
network are each adapted to support a plurality of beams of a signal beam-forming
scheme and to communicate with a wireless communication device using at least one
of the plurality of beams (the serving beam).
[0068] The method comprises identifying one or more candidate beams, causing transmission
of a reference signal on each of the candidate beams, and causing the communication
with the wireless communication device to use a target beam, wherein one of the candidate
beams is selected as the target beam based on a report from the wireless communication
device, and wherein the report is indicative of a result of measurements of the reference
signals.
[0069] Causing the communication with the wireless communication device to use a target
beam comprises causing transmission, on the target beam, of a beam switch command
to the wireless communication device.
[0070] Causing transmission of a beam switch command to the wireless communication device
may comprise transmitting the beam switch command to the wireless communication device
if the target beam is supported by the network node.
[0071] Causing transmission of a beam switch command to the wireless communication device
may comprise performing a handover of the wireless communication device to the target
beam supporting network node if the target beam is supported by an other, target beam
supporting, network node.
[0072] Performing a handover of the wireless communication device to the target beam supporting
network node may, according to some embodiments, comprise causing the target beam
supporting network node to transmit a handover command to the wireless communication
device. The handover command may be a beam switch command in that it may comprise
an indication of which beam is the target beam.
[0073] Other aspects are a computer program product, an arrangement and a network node having
features identical with or corresponding to those of the eighth aspect.
[0074] In some embodiments, any of the above aspects may additionally have features identical
with or corresponding to any of the various features as explained above for any of
the other aspects, as suitable.
[0075] An advantage of some embodiments is that the possibility to complete a beam switch
(or any other appropriate part of a mobility procedure) is improved.
Brief Description of the Drawings
[0076] Further objects, features and advantages will appear from the following detailed
description of embodiments, with reference being made to the accompanying drawings,
in which:
Fig. 1 is a schematic drawing illustrating an example scenario where some embodiments
may be applicable;
Fig. 2 is a signaling diagram illustrating example signaling and method steps according
to some embodiments;
Fig. 3 is a flowchart illustrating example method steps according to some embodiments;
Fig. 4 is a block diagram illustrating an example arrangement according to some embodiments;
Fig. 5 is a block diagram illustrating an example arrangement according to some embodiments;
and
Fig. 6 is a schematic drawing illustrating a computer readable medium according to
some embodiments.
Detailed Description
[0077] In the following, embodiments will be described in which a beam-forming system applies
an approach where a measurement report of a mobility procedure may be sent from the
wireless communication device to the network on a beam other than the serving beam
(typically the prospect target beam) to enable a mobility procedure being carried
out.
[0078] This is particularly beneficial when the signal-to-interference ratio (SIR) of the
serving beam drops drastically, such that there is not enough time to carry out the
mobility procedure before the signal-to-interference ratio is so bad that reliable
communication via the serving beam is not possible. Thus, the approach may be seen
as a very fast link recovery process.
[0079] Figure 2 illustrates example signaling and method steps of a network node (NWN1,
compare with network node 120 of Figure 1) 200 supporting the serving beam, a wireless
communication device (WCD, compare with the wireless communication device 100a, 100b
of Figure 1) 240, and another network node (NWN2, compare with network node 121 of
Figure 1) 220.
[0080] During transmission of data from the network node 200 to the wireless communication
device 240 via the serving beam, the wireless communication device 240 may send signal
quality indications to the network node 200. The signal quality indications may be
transmitted in a regular fashion (e.g. CQI, CSI, etc.) and/or when the wireless communication
device detects that the signal quality is low/decreasing (e.g. SIR below a threshold,
expected message - e.g. ACK/NAK - not received, inability to decode received data,
etc.).
[0081] When the network node 200 detects decreasing/low signal quality (e.g. based on SIR
measurements, received CSI, received CQI, or similar) or when the network node 200
receives an indication that the wireless communication device 240 has detected decreasing/low
signal quality, the network node 200 may initiate a mobility procedure in step 202.
[0082] Execution of the mobility procedure is represented in Figure 2 by selection by the
network node 200 of candidate beams (e.g. from a database as described above) in step
204, activating MRS (mobile reference signal) on each of the candidate beams (which
may include transmitting a request for MRS signaling 230 to other network nodes supporting
candidate beams), MRS signaling 231, 232 by the candidate beams, measurement configuration
234 of the wireless communication device, measurements on the MRS by the wireless
communication device 240 in step 206, reporting MRS measurements 235 to the network
node 200 supporting the serving beam, taking a beam switch decision by the network
node supporting the serving beam 200 including selection of target beam in step 208,
and performing the beam switch 210 as applicable (which may include a handover to
another network node depending on which network node supports the target beam of the
beam switch). Numerous variations compared to the execution of the mobility procedure
described here may be envisioned. For example, other steps and/or signals may also
be present (e.g. acknowledgement of measurement configuration 234, MRS request 230,
report 235, signaling in connection to the beam switch/handover, etc.).
[0083] As explained above, Figure 1 describes a scenario where the signal-to-interference
ratio drops very quickly due to a sudden shadowing effect (moving around a corner
in the example of Figure 1). If this happens during execution of the mobility procedure
(e.g. as described in Figure 2), there may not be enough time to carry out the mobility
procedure before the signal-to-interference ratio is so bad that reliable communication
via the serving beam is not possible (e.g. radio link failure, RLF). For example,
the connection may be lost before a beam switch command has been transmitted (to the
wireless communication device) and acknowledged, before the report 235 has been transmitted
(by the wireless communication device) and acknowledged, before the measurement configuration
of the wireless communication device and acknowledgement thereof, etc.
[0084] Therefore, uplink resources (for conveying the measurement report 235) are reserved,
according to some embodiments, on some or all of the candidate beams as illustrated
by step 205. Step 205 may be performed by the serving network node 200 and/or by another
network node 220 (e.g. the one supporting a candidate beam or a separate network node
comprising a scheduler). Information regarding the reserved uplink resources may be
communicated to the wireless communication device 240 (e.g. in the measurement configuration
234, in the MRS signaling 231, 232, or in a separate message). The report of the MRS
measurements may then be sent on one or more of the reserved uplink resources. Thus,
depending on whether the candidate beam having the reserved uplink resource is supported
by the serving node 200 or another network node 220, the report may be sent to the
serving node as illustrated by 235 or to another network node as illustrated by 236.
A beam switch command of step 210 may be transmitted to the wireless communication
device using one of the candidate beams (e.g. the target beam).
[0085] Figure 3 illustrates and example method 300 according to some embodiments. The method
300 is for a network node (e.g. network node 120 of Figure 1 and/or network node 200
of Figure 2) of a cellular communication network, wherein network nodes of the cellular
communication network are each adapted to support a plurality of beams of a signal
beam-forming scheme and to communicate with a wireless communication device (e.g.
wireless communication device 100a, 100b of Figure 1 and/or wireless communication
device 240 of Figure 2) using one of the plurality of beams.
[0086] In step 310, a loss of the serving beam (or a risk thereof) is detected. The detection
may, for example, comprise lack of receipt of an expected message according to an
ongoing mobility procedure (compare with the mobility procedure of Figure 2), and/or
detection of a decreasing/low signal quality (e.g. based on uplink signal-to-interference
- SIR - measurements, received quality indications such as CQI - channel quality indication
- or CSI - channel state information - from the wireless communication device, notification
from the wireless communication device of decoding problem, etc.). Alternatively or
additionally, the detection of step 310 may be based on statistics (e.g. of the database
described above) regarding SIR and/or RLF at a current location of the wireless communication
device.
[0087] In step 320 one or more candidate beams for the mobility procedure are identified
(compare with step 204 of Figure 2) and reference signals are transmitted thereon
(compare with 230, 231, 232 of Figure 2).
[0088] In some embodiments, one or more of steps 320 and 330 may be performed before step
310.
[0089] When loss of the serving beam (or a risk thereof) is detected, step 310, uplink resources
are reserved on each of the candidate beams as illustrated by step 340 (compare with
step 205 of Figure 2). Step 340 may be performed before step 330 in some embodiments.
[0090] An indication of the reserved uplink resources may be conveyed to the wireless communication
device (e.g. as part of the reference signaling) according to step 350 or may be implied
to the wireless communication device.
[0091] The wireless communication device performs measurements on the reference signals
(compare with step 206 of Figure 2) and transmits a measurement report to the network
(compare with 235, 236 of Figure 2). Since the link of the serving beam is lost (or
very week), the report is transmitted using one or more of the reserved uplink resources.
Typically, the uplink resource of the candidate beam showing the most promising measurements
may be used to transmit the report.
[0092] In step 360, the report is either received directly by the network node if it is
transmitted on a beam supported by that network node, or the report or an indication
of its content may be received from another network node that supports the beam on
which the report was transmitted.
[0093] A beam switch to the most promising beam (the target beam, selected from the candidate
beams based on the report) is then conducted in step 370 as applicable (compare with
steps 208 and 210 of Figure 2).
[0094] Steps 330 and 340 may differ somewhat for candidate beams supported by the network
node carrying out the method 200 and for candidate beams supported by another network
node. In the first case, the network node simply reserves the uplink resource and
transmits the reference signal on the candidate beam. In the second case, the reservation
of the uplink resource and the transmission of the reference signal involve signaling
between the serving network node and the network node supporting the candidate beam
(e.g. instructions/requests from the serving network node to reserve uplink resources
and transmit the reference signal and acknowledgements thereof from the other network
node).
[0095] The beam switch decision and/or the beam switch control (e.g. transmission of a beam
switch (possibly including handover) command to the wireless communication device)
may be performed by the serving network node or by another network node.
[0096] In the case where the measurement report is received on a beam supported by the serving
network node, the beam switch decision is typically made by the serving network node.
On the other hand, if the measurement report is received on a beam supported by another
network node than the serving network node, the beam switch decision may be made by
that network node or by the serving network node (after conveying the measurements
report content to the serving network node).
[0097] The beam switch command is typically transmitted using the target beam. If the target
beam (or more generally, the beam to be used for the beam switch command) is on another
network node than the one making the beam switch decision, suitable signaling between
the two involved network nodes is implied.
[0098] Generally, the beam switch may be performed without explicit involvement of the wireless
communication device, i.e. without sending any beam switch command at all to the wireless
communication device.
[0099] Also generally, a timer function may be implemented after the measurement process
is completed (e.g. after step 350 or 360) which is to be applied if no suitable target
beam is found based on the measurements. Such a timer function may have an associated
maximum time that is, typically known to both the network and the wireless communication
device. Searching for a suitable target beam may continue until the maximum time has
elapsed, and then a radio link failure occurs.
[0100] Figures 4 and 5 illustrate example arrangements for a network node (e.g. network
node 120 of Figure 1) of a cellular communication network, wherein network nodes of
the cellular communication network are each adapted to support a plurality of beams
of a signal beam-forming scheme and to communicate with a wireless communication device
(e.g. wireless communication device 100a, 100b of Figure 1) using one of the plurality
of beams. The arrangements of Figures 4 and 4 may, for example, be adapted to execute
(or at least cause execution of) the various method steps described in connection
to Figure 3.
[0101] The arrangement of Figure 4 comprises a controller (CNTR) 400 operatively connected
to a transceiver (RX/TX) 410 for transmission and reception of suitable signals, which
transceiver may or may not be comprised in the arrangement.
[0102] Figure 5 shows an example controller (CNTR) 500 which may or may not be an implementation
of the controller 400 of Figure 4.
[0103] The controller 500 may comprise a mobility manager (MM) 520 adapted to initiate and
control a mobility procedure.
[0104] The controller 400, 500 is adapted to detect (risk of) loss of a connection supported
by a serving beam (compare with step 310 of Figure 3).
[0105] The controller 500 may comprise a quality monitor (Q MON) 550 adapted to monitor
a signal quality of the communication link, where detection of a risk of losing a
connection may comprise detection of a decreasing (or low) signal quality.
[0106] Alternatively or additionally, the controller 500 may be associated with a database
(DB) 515 comprising information as described above. The information in the database
may be used to detect (risk of) loss of a connection as explained above.
[0107] Yet alternatively or additionally, the mobility manager 520 may be adapted to detect
loss of a connection by detecting lack of an expected signal according to an ongoing
mobility procedure.
[0108] The controller 400, 500 is also adapted to cause identification of one or more candidate
beams (compare with step 320 of Figure 3). For example, the controller 400, 500 may
be adapted to identify the candidate beams. To this end, the controller 500 may comprise
a beam selector (BEAM SEL) 530 adapted to identify the candidate beams. The controller
400, 500 is further adapted to cause transmission of (e.g. transmit) a reference signal
on each of the candidate beams (compare with step 330 of Figure 3).
[0109] As explained above, the candidate beams may be provided by a database (DB) 515. The
database may be comprised in, or otherwise associated with, the network node. For
example, the database may be a cloud-based service shared by some or all of the network
nodes of the cellular communication system.
[0110] The controller 400, 500 is also adapted to cause reservation of the uplink resource
of each of the candidate beams as explained above (compare with step 340 of Figure
3). To this end the controller 500 may comprise a scheduler (SCH) 540 adapted to reserve
the uplink resources for candidate beams supported by the serving network node.
[0111] The controller 400, 500 is further adapted to cause the communication with the wireless
communication device to use a target beam (compare with step 370 of Figure 3), wherein
one of the candidate beams is selected as the target beam based on the conveyed report
as explained above.
[0112] An arrangement for a wireless communication device adapted to communicate with a
network node of a cellular communication network as described above may also comprise
a controller. The controller may be adapted to cause the wireless communication device
to perform measurements of reference signals received on each of one or more identified
candidate beams and to transmit a report indicative of a result of the measurements
in a reserved uplink resource of one of the candidate beams
[0113] A few examples of different variations of the above-described embodiments will now
be given.
[0114] In active mode, the wireless communication device continuously receives and decodes
control information and data information and estimates the SIR of the connection.
As part of a mobility procedure, the network provides the wireless communication device
with candidate beams to measure on. The wireless communication device may detect that
the connection via the serving beam is lost if, for example, the control signal cannot
be decoded or the estimated SIR is below a threshold. The network may detect that
the connection via the serving beam is lost if, for example, the wireless communication
device report so (providing only the downlink is bad) or uplink transmissions cannot
be successfully decoded.
[0115] As can be seen in Figure 2 and the related text, several messages need to be transmitted
from the network node supporting the serving beam to the wireless communication device
and vice versa. When there is a sudden loss of the serving radio link, the sequence
of messages may be interrupted at various points, for example:
- 1. The serving node does not receive an acknowledgment of the measurement configuration
234. This may imply to the serving node that the measurement configuration was not
received by the wireless communication device or that the acknowledgment was transmitted
by the wireless communication device but not received.
- 2. The measurement report 235 is not received by the serving node. In this case, the
serving node does not know the quality of the candidate beams.
- 3. The wireless communication device does not receive an acknowledgment of the measurement
report 235. In this case, the wireless communication device knows the quality of the
candidate beams, but it is not clear to the wireless communication device whether
the serving node has received that information.
- 4. The serving node does not receive an acknowledgment of a handover (or beam switch)
command from the wireless communication device. This may imply to the serving node
that the handover command was not received by the wireless communication device or
that the acknowledgment was transmitted by the wireless communication device but not
received. In this case, the wireless communication device does not know to which beam
it should switch, or what radio resources it should use.
[0116] Without application of embodiments described herein the wireless communication device
typically must perform a normal random access procedure to restore the connection
if any of the events occurs. Such a random access procedure is typically quite time
consuming and not desirable in these circumstances.
[0117] Since the mobility procedure is interrupted if any of the events occurs, not all
messages can be transmitted from the serving node to the wireless communication device
and vice versa. Thus, the information needs to be otherwise made available.
[0118] If the process is interrupted, one or more of the following steps may be applied
by the serving node:
- Request retransmission of the MRS on the candidate beams (compare with step 330 of
Figure 3).
- Reserve uplink resources on candidate beams for measurement report (compare with step
340 of Figure 3).
- Optionally, send indication of reserved resources to the wireless communication device
in the MRS (compare with step 350 of Figure 3).
- When the measurement report is received, send beam switch command on target beam.
[0119] If the interruption is according to event 1 or 2 described above, the above steps
may be performed for all candidate beams, if the interruption is according to event
3 described above, the above steps may be performed for all, some, or only one of
the candidate beams (typically for the strongest as indicated by the report), and
if the interruption is according to event 4 described above, the above steps (or at
least the last one) may be performed for all, some, or only one of the candidate beams
(typically only for the selected beam).
[0120] If the process is interrupted, one or more of the following steps may be applied
by the wireless communication device:
- Do (or redo) measurements on the candidate beams.
- Send report on an uplink resource indicated in the MRS of one of the candidate beams
(typically the strongest).
- Listen for beam switch command on candidate beams.
[0121] If the interruption is according to event 1 described above, the measurements may
be performed blindly or using a most recent candidate beam list available to the wireless
communication device. If the interruption is according to event 2 or 3 described above,
the measurements may be performed starting with the strongest candidate beam according
to the previous measurement. If the interruption is according to event 4 described
above, the measurements may (if performed at all) be performed starting with the strongest
candidate beam according to the previous measurement.
[0122] The described embodiments and their equivalents may be realized in software or hardware
or a combination thereof. They may be performed by general-purpose circuits associated
with or integral to a communication device, such as digital signal processors (DSP),
central processing units (CPU), co-processor units, field-programmable gate arrays
(FPGA) or other programmable hardware, or by specialized circuits such as for example
application-specific integrated circuits (ASIC). All such forms are contemplated to
be within the scope of this disclosure.
[0123] Embodiments may appear within an electronic apparatus (such as a wireless communication
device or a network node) comprising circuitry/logic or performing methods according
to any of the embodiments. The electronic apparatus may, for example, be a mobile
radio communication equipment, a mobile telephone, a base station, a base station
controller, a communicator, an electronic organizer, a smartphone, a computer, a notebook,
or a mobile gaming device.
[0124] According to some embodiments, a computer program product comprises a computer readable
medium such as, for example, a USB-stick, a plug-in card, an embedded drive, or a
read-only memory (ROM) such as the CD-ROM 600 illustrated in Figure 6. The computer
readable medium may have stored thereon a computer program comprising program instructions.
The computer program may be loadable into a data-processing unit (PROC) 610, which
may, for example, be comprised in a wireless communication device or a network node
630. When loaded into the data-processing unit, the computer program may be stored
in a memory (MEM) 620 associated with or integral to the data-processing unit. According
to some embodiments, the computer program may, when loaded into and run by the data-processing
unit, cause the data-processing unit to execute method steps according to, for example,
the methods shown in any of the Figures 2 and 3.
[0125] Reference has been made herein to various embodiments. However, a person skilled
in the art would recognize numerous variations to the described embodiments that would
still fall within the scope of the claims. For example, the method embodiments described
herein describes example methods through method steps being performed in a certain
order. However, it is recognized that these sequences of events may take place in
another order without departing from the scope of the claims. Furthermore, some method
steps may be performed in parallel even though they have been described as being performed
in sequence.
[0126] In the same manner, it should be noted that in the description of embodiments, the
partition of functional blocks into particular units is by no means limiting.
[0127] Contrarily, these partitions are merely examples. Functional blocks described herein
as one unit may be split into two or more units. In the same manner, functional blocks
that are described herein as being implemented as two or more units may be implemented
as a single unit without departing from the scope of the claims.
[0128] Hence, it should be understood that the details of the described embodiments are
merely for illustrative purpose and by no means limiting. Instead, all variations
that fall within the range of the claims are intended to be embraced therein.
1. A method for switching beams in a network node (120, 200) of a cellular communication
network, wherein the network node and at least some other network nodes of the cellular
communication network are each adapted to support a plurality of beams of a signal
beam-forming scheme and to communicate with a wireless communication device (240)
using at least one of the plurality of beams, the method comprising:
identifying (320, 204) responsive to detecting failure of a mobility procedure, one
or more candidate beams (111, 112) for beam switch ;
causing (330) transmission of a reference signal (231, 232) on each of the candidate
beams;
causing (340) reservation of an uplink resource of at least one of the candidate beams,
wherein the uplink resources are for conveying a report (235) from the wireless communication
device, and wherein the report is indicative of a result of measurements of the reference
signals; and
causing (370, 210) the communication with the wireless communication device to switch
from a serving beam to a target beam, wherein one of the candidate beams is selected
as the target beam based on the conveyed report.
2. The method of claim 1 further comprising detecting (310) a decreasing signal quality,
and wherein at least the causing of reservation of uplink resources is performed in
response to detecting the decreased signal quality.
3. The method of any of claims 1 through 2 wherein at least the causing of reservation
of uplink resources is performed in response to detecting (310) a failure of a mobility
procedure.
4. The method of any of claims 1 through 3 further comprising causing (350) transmission
of an indication regarding the reservation of uplink resources to the wireless communication
device.
5. The method of any of claim 1 through 4 wherein the selection of one of the candidate
beams as the target beam comprises selection of the one of the candidate beams on
which the report is conveyed in the reserved uplink resource.
6. The method of any of claims 1 through 5 wherein, for a candidate beam supported by
the network node,
causing transmission of the reference signal on the candidate beam comprises transmitting
the reference signal; and
causing reservation of the uplink resource on the candidate beams comprises reserving
the uplink resource.
7. The method of any of claims 1 through 6 wherein, for a candidate beam supported by
an other, candidate beam supporting, network node,
causing transmission of the reference signal on the candidate beam comprises transmitting
a reference signal request to the candidate beam supporting network node; and
causing reservation of the uplink resource on the candidate beams comprises transmitting
an uplink resource request to the candidate beam supporting network node.
8. The method of any of claims 1 trough 7 wherein causing the communication with the
wireless communication device to use a target beam comprises causing transmission
of a beam switch command to the wireless communication device.
9. A method for a wireless communication device (240) adapted to communicate with a network
node (120, 200) of a cellular communication network, wherein the network node and
at least some other network nodes of the cellular communication network are each adapted
to support a plurality of beams of a signal beam-forming scheme and to communicate
with the wireless communication device using at least one of the plurality of beams,
the method comprising:
performing measurements (206) of reference signals (231, 232) received on each of
one or more identified candidate beams (111, 112) for a beam switch, wherein at least
one of the one or more identified candidate beams has a reserved uplink resource for
conveying a report from the wireless communication device; and
transmitting the report (235) in one of the reserved uplink resources, wherein the
report is indicative of a result of the measurements, wherein the report is for selection
of one of the candidate beams as a target beam, and wherein the target beam is for
use in communication with the cellular communication network.
10. The method of claim 9 further comprising receiving an indication regarding the reservation
of uplink resources from the cellular communication network.
11. The method of any of claims 9 through 10 wherein the report is transmitted in the
reserved uplink resource of a candidate beam to be selected as the target beam.
12. A computer program product comprising a computer readable medium (600), having thereon
a computer program comprising program instructions, the computer program being loadable
into a data-processing unit and adapted to cause execution of the method according
to any of claims 1 through 11 when the computer program is run by the data-processing
unit.
13. An arrangement for a network node of a cellular communication network, wherein the
network node and at least some other network nodes of the cellular communication network
are each adapted to support a plurality of beams of a signal beam-forming scheme and
to communicate with a wireless communication device using at least one of the plurality
of beams, the arrangement comprising a controller (400, 500) adapted to cause:
identification of one or more candidate beams for a beam switch, responsive to detecting
failure of a mobility procedure;
transmission of a reference signal on each of the candidate beams;
reservation of an uplink resource of at least one of the candidate beams,
wherein the uplink resources is for conveying a report from the wireless communication
device, and wherein the report is indicative of a result of measurements of the reference
signals; and
the communication with the wireless communication device to switch from a serving
beam to a target beam, wherein one of the candidate beams is selected as the target
beam based on the conveyed report.
14. The arrangement of claim 13 wherein the controller is further adapted to cause detection
of a decreasing signal quality, and wherein at least the causing of reservation of
uplink resources is performed in response to detecting the decreased signal quality.
15. The arrangement of any of claims 13 through 14 wherein at least the causing of reservation
of uplink resources is performed in response to the controller detecting a failure
of a mobility procedure.
16. The arrangement of any of claims 13 through 15 wherein the controller is further adapted
to cause transmission of an indication regarding the reservation of uplink resources
to the wireless communication device.
17. The arrangement of any of claim 13 through 16 wherein the selection of one of the
candidate beams as the target beam comprises selection of the one of the candidate
beams on which the report is conveyed in the reserved uplink resource.
18. The arrangement of any of claims 13 through 17 wherein, for a candidate beam supported
by the network node,
causing transmission of the reference signal on the candidate beam comprises transmitting
the reference signal; and
causing reservation of the uplink resource on the candidate beams comprises reserving
the uplink resource.
19. The arrangement of any of claims 13 through 18 wherein, for a candidate beam supported
by an other, candidate beam supporting, network node,
causing transmission of the reference signal on the candidate beam comprises transmitting
a reference signal request to the candidate beam supporting network node; and
causing reservation of the uplink resource on the candidate beams comprises transmitting
an uplink resource request to the candidate beam supporting network node.
20. A network node of a cellular communication network comprising the arrangement according
to any of claims 13 through 19.
21. An arrangement for a wireless communication device adapted to communicate with a network
node of a cellular communication network, wherein the network node and at least some
other network nodes of the cellular communication network are each adapted to support
a plurality of beams of a signal beam-forming scheme and to communicate with the wireless
communication device using at least one of the plurality of beams, the arrangement
comprising a controller (400) adapted to cause:
performing of measurements of reference signals received on each of one or more identified
candidate for a beam switch, wherein at least one of the one or more identified candidate
beams has a reserved uplink resource for conveying a report from the wireless communication
device; and
transmission of the report in one of the reserved uplink resources, wherein the report
is indicative of a result of the measurements, wherein the report is for selection
of one of the candidate beams as a target beam, and wherein the target beam is for
use in communication with the cellular communication network.
22. The arrangement of claim 21 wherein the controller is further adapted to cause reception
of an indication regarding the reservation of uplink resources from the cellular communication
network.
23. The arrangement of any of claims 21 through 22 wherein the controller is adapted to
cause transmission of the report in the reserved uplink resource of a candidate beam
to be selected as the target beam.
24. A wireless communication device comprising the arrangement according to any of claims
21 through 23.
1. Verfahren zum Umschalten von Strahlen in einem Netzwerkknoten (120, 200) eines zellularen
Kommunikationsnetzwerks; wobei der Netzwerkknoten und mindestens einige andere Netzwerkknoten
des zellularen Kommunikationsnetzwerks jeweils dafür ausgelegt sind, mehrere Strahlen
eines Signalstrahlformungsschemas zu unterstützen und mit einer drahtlosen Kommunikationsvorrichtung
(240) unter Verwendung mindestens eines der Vielzahl von Strahlen zu kommunizieren,
wobei das Verfahren Folgendes umfasst:
Identifizieren (320, 204), als Reaktion auf das Erfassen eines Fehlers eines Mobilitätsverfahrens,
eines oder mehrerer Kandidatenstrahlen (111, 112) zur Strahlumschaltung;
Verursachen (330) der Übertragung eines Referenzsignals (231, 232) auf jedem der Kandidatenstrahlen;
Verursachen einer (340) Reservierung einer Uplink-Ressource von mindestens einem der
Kandidatenstrahlen, wobei die Uplink-Ressourcen zum Übermitteln eines Berichts (235)
von der drahtlosen Kommunikationsvorrichtung dienen und wobei der Bericht ein Ergebnis
von Messungen der Referenzsignale anzeigt; und
Verursachen, dass (370, 210) die Kommunikation mit der drahtlosen Kommunikationsvorrichtung
von einem Dienststrahl zu einem Zielstrahl umschaltet, wobei einer der Kandidatenstrahlen
basierend auf dem übermittelten Bericht als Zielstrahl ausgewählt wird.
2. Verfahren nach Anspruch 1, das ferner das Erfassen (310) einer abnehmenden Signalqualität
umfasst und wobei zumindest das Verursachen einer Reservierung von Uplink-Ressourcen
als Reaktion auf das Erfassen der verringerten Signalqualität durchgeführt wird.
3. Verfahren nach einem der Ansprüche 1 bis 2, wobei mindestens das Verursachen einer
Reservierung von Uplink-Ressourcen als Reaktion auf das Erfassen (310) eines Fehlers
eines Mobilitätsverfahrens durchgeführt wird.
4. Verfahren nach einem der Ansprüche 1 bis 3, das ferner das Verursachen (350) der Übertragung
einer Anzeige bezüglich der Reservierung von Uplink-Ressourcen an die drahtlose Kommunikationsvorrichtung
umfasst.
5. Verfahren nach einem der Ansprüche 1 bis 4, wobei die Auswahl eines der Kandidatenstrahlen
als Zielstrahl die Auswahl eines der Kandidatenstrahlen umfasst, auf denen der Bericht
in der reservierten Uplink-Ressource übertragen wird.
6. Verfahren nach einem der Ansprüche 1 bis 5, wobei für einen vom Netzwerkknoten unterstützten
Kandidatenstrahl Folgendes gilt:
das Verursachen der Übertragung des Referenzsignals auf dem Kandidatenstrahl umfasst
das Übertragen des Referenzsignals; und
das Verursachen der Reservierung der Uplink-Ressource auf den Kandidatenstrahlen umfasst
das Reservieren der Uplink-Ressource.
7. Verfahren nach einem der Ansprüche 1 bis 6, wobei für einen Kandidatenstrahl, der
von einem anderen Kandidatenstrahl-unterstützenden Netzwerkknoten unterstützt wird,
Folgendes gilt:
das Verursachen der Übertragung des Referenzsignals auf dem Kandidatenstrahl umfasst
das Übertragen einer Referenzsignalanforderung an den Kandidatenstrahl-unterstützenden
Netzwercknoten; und
das Verursachen der Reservierung der Uplink-Ressource auf den Kandidatenstrahlen umfasst
das Übertragen einer Uplink-Ressourcen-Anforderung an den Kandidatenstrahl-unterstützenden
Netzwerkknoten.
8. Verfahren nach einem der Ansprüche 1 bis 7, wobei das Verursachen, dass die Kommunikation
mit der drahtlosen Kommunikationsvorrichtung einen Zielstrahl verwendet, das Verursachen
der Übertragung eines Strahlumschaltbefehls an die drahtlose Kommunikationsvorrichtung
umfasst.
9. Verfahren für eine drahtlose Kommunikationsvorrichtung (240), die zur Kommunikation
mit einem Netzwerkknoten (120, 200) eines zellularen Kommunikationsnetzwerks ausgelegt
ist; wobei der Netzwerkknoten und mindestens einige andere Netzwerkknoten des zellularen
Kommunikationsnetzwerks jeweils dafür ausgelegt sind, mehrere Strahlen eines Signalstrahlformungsschemas
zu unterstützen und mit der drahtlosen Kommunikationsvorrichtung unter Verwendung
mindestens eines der Vielzahl von Strahlen zu kommunizieren, wobei das Verfahren Folgendes
umfasst:
Durchführen von Messungen (206) von Referenzsignalen (231, 232), die an jedem oder
mehreren identifizierten Kandidatenstrahlen (111, 112) für eine Strahlumschaltung
empfangen wurden,
wobei mindestens einer der einen oder mehreren identifizierten Kandidatenstrahlen
eine reservierte Uplink-Ressource zum Übermitteln eines Berichts von der drahtlosen
Kommunikationsvorrichtung aufweist; und
Übertragen des Berichts (235) in einer der reservierten Uplink-Ressourcen, wobei der
Bericht ein Ergebnis der Messungen anzeigt, wobei der Bericht zur Auswahl eines der
Kandidatenstrahlen als Zielstrahl dient, und wobei der Zielstrahl zur Verwendung bei
der Kommunikation mit dem zellularen Kommunikationsnetzwerk verwendet wird.
10. Verfahren nach Anspruch 9, das ferner das Empfangen einer Anzeige bezüglich der Reservierung
von Uplink-Ressourcen von dem zellularen Kommunikationsnetzwerk umfasst.
11. Verfahren nach einem der Ansprüche 9 bis 10, wobei der Bericht in der reservierten
Uplink-Ressource eines Kandidatenstrahls übertragen wird, der als Zielstrahl ausgewählt
werden soll.
12. Computerprogrammprodukt, das ein computerlesbares Medium (600) umfasst, auf dem sich
ein Computerprogramm befindet, das Programmanweisungen umfasst; wobei das Computerprogramm
in eine Datenverarbeitungseinheit geladen werden kann und dafür ausgelegt, die Ausführung
des Verfahrens gemäß einem der Ansprüche 1 bis 11 zu bewirken, wenn das Computerprogramm
von der Datenverarbeitungseinheit ausgeführt wird.
13. Anordnung für einen Netzwerkknoten eines zellularen Kommunikationsnetzwerks, wobei
der Netzwerkknoten und mindestens einige andere Netzwerkknoten des zellularen Kommunikationsnetzwerks
jeweils dafür ausgelegt sind, mehrere Strahlen eines Signalstrahlformungsschemas zu
unterstützen und mit einer drahtlosen Kommunikationsvorrichtung unter Verwendung mindestens
eines der Vielzahl von Strahlen zu kommunizieren, wobei die Anordnung eine Steuerung
(400, 500) umfasst, die dafür ausgelegt ist, Folgendes zu verursachen:
Identifizieren eines oder mehrerer Kandidatenstrahlen für eine Strahlumschaltung als
Reaktion auf das Erfassen eines Fehlers eines Mobilitätsverfahrens;
Übertragung eines Referenzsignals auf jedem der Kandidatenstrahlen;
Reservierung einer Uplink-Ressource von mindestens einem der Kandidatenstrahlen, wobei
die Uplink-Ressourcen zum Übermitteln eines Berichts von der drahtlosen Kommunikationsvorrichtung
dienen und der Bericht ein Ergebnis von Messungen der Referenzsignale anzeigt; und
die Kommunikation mit der drahtlosen Kommunikationsvorrichtung, um von einem Dienststrahl
zu einem Zielstrahl umzuschalten, wobei einer der Kandidatenstrahlen basierend auf
dem übermittelten Bericht als Zielstrahl ausgewählt wird.
14. Anordnung nach Anspruch 13, wobei die Steuerung ferner dafür ausgelegt ist, die Erfassung
einer abnehmenden Signalqualität zu bewirken, und wobei zumindest das Verursachen
einer Reservierung von Uplink-Ressourcen als Reaktion auf das Erfassen der verringerten
Signalqualität durchgeführt wird.
15. Anordnung nach einem der Ansprüche 13 bis 14, wobei mindestens das Verursachen einer
Reservierung von Uplink-Ressourcen als Reaktion darauf durchgeführt wird, dass die
Steuerung einen Fehler eines Mobilitätsverfahrens erfasst.
16. Anordnung nach einem der Ansprüche 13 bis 15, wobei die Steuerung ferner dafür ausgelegt
ist, die Übertragung einer Anzeige bezüglich der Reservierung von Uplink-Ressourcen
an die drahtlose Kommunikationsvorrichtung zu bewirken.
17. Anordnung nach einem der Ansprüche 13 bis 16, wobei die Auswahl eines der Kandidatenstrahlen
als Zielstrahl die Auswahl eines der Kandidatenstrahlen umfasst, auf denen der Bericht
in der reservierten Uplink-Ressource übertragen wird.
18. Anordnung nach einem der Ansprüche 13 bis 17, wobei für einen vom Netzwerkknoten unterstützten
Kandidatenstrahl Folgendes gilt:
das Verursachen der Übertragung des Referenzsignals auf dem Kandidatenstrahl umfasst
das Übertragen des Referenzsignals; und
das Verursachen der Reservierung der Uplink-Ressource auf den Kandidatenstrahlen umfasst
das Reservieren der Uplink-Ressource.
19. Anordnung nach einem der Ansprüche 13 bis 18, wobei für einen Kandidatenstrahl, der
von einem anderen Kandidatenstrahl-unterstützenden Netzwerkknoten unterstützt wird,
Folgendes gilt:
das Verursachen der Übertragung des Referenzsignals auf dem Kandidatenstrahl umfasst
das Übertragen einer Referenzsignalanforderung an den Kandidatenstrahl-unterstützenden
Netzwercknoten; und
das Verursachen einer Reservierung der Uplink-Ressource auf den Kandidatenstrahlen
umfasst das Übertragen einer Uplink-Ressourcen-Anforderung an den Kandidatenstrahl-unterstützenden
Netzwerkknoten.
20. Netzwerkknoten eines zellularen Kommunikationsnetzwerks, das die Anordnung nach einem
der Ansprüche 13 bis 19 umfasst.
21. Anordnung für eine drahtlose Kommunikationsvorrichtung, die zur Kommunikation mit
einem Netzwerkknoten eines zellularen Kommunikationsnetzwerks ausgelegt ist; wobei
der Netzwerkknoten und mindestens einige andere Netzwerkknoten des zellularen Kommunikationsnetzwerks
jeweils dafür ausgelegt sind, mehrere Strahlen eines Signalstrahlformungsschemas zu
unterstützen und mit der drahtlosen Kommunikationsvorrichtung unter Verwendung mindestens
eines der Vielzahl von Strahlen zu kommunizieren, wobei die Anordnung eine Steuerung
(400) umfasst, die dafür ausgelegt ist, Folgendes zu verursachen:
Durchführen von Messungen von Referenzsignalen, die an jedem oder mehreren identifizierten
Kandidaten für eine Strahlumschaltung empfangen wurden, wobei mindestens einer der
einen oder mehreren identifizierten Kandidatenstrahlen eine reservierte Uplink-Ressource
zum Übermitteln eines Berichts von der drahtlosen Kommunikationsvorrichtung aufweist;
und
Übertragen des Berichts in einer der reservierten Uplink-Ressourcen, wobei der Bericht
ein Ergebnis der Messungen anzeigt, wobei der Bericht zur Auswahl eines der Kandidatenstrahlen
als Zielstrahl dient und wobei der Zielstrahl zur Verwendung bei der Kommunikation
mit dem zellularen Kommunikationsnetzwerk verwendet wird.
22. Anordnung nach Anspruch 21, wobei die Steuerung ferner dafür ausgelegt ist, den Empfang
einer Anzeige bezüglich der Reservierung von Uplink-Ressourcen von dem zellularen
Kommunikationsnetzwerk zu bewirken.
23. Anordnung nach einem der Ansprüche 21 bis 22, wobei die Steuerung dafür ausgelegt
ist, zu bewirken, dass die Übertragung des Berichts in der reservierten Uplink-Ressource
eines Kandidatenstrahls als Zielstrahl ausgewählt wird.
24. Drahtlose Kommunikationsvorrichtung, die die Anordnung nach einem der Ansprüche 21
bis 23 umfasst.
1. Procédé de commutation de faisceaux dans un nœud de réseau (120, 200) d'un réseau
de communication cellulaire, dans lequel le nœud de réseau et au moins certains autres
nœuds de réseau de réseau de communication cellulaire sont chacun adaptés pour supporter
une pluralité de faisceaux d'un schéma de formation de faisceau de signaux et pour
communiquer avec un dispositif de communication sans fil (240) en utilisant au moins
l'un de la pluralité de faisceaux, le procédé comprenant :
l'identification (320, 204) sensible à la détection de l'échec d'une procédure de
mobilité, d'un ou plusieurs faisceaux candidats (111, 112) pour le commutateur de
faisceaux ;
la provocation de (330) la transmission d'un signal de référence (231, 232) sur chacun
des faisceaux candidats ;
la provocation de (340) la réservation d'une ressource de liaison montante d'au moins
l'un des faisceaux candidats, où les ressources de liaison montante sont destinées
à transmettre un rapport (235) à partir du dispositif de communication sans fil, et
où le rapport indique un résultat de mesures des signaux de référence ; et
la provocation de (370, 210) la communication avec le dispositif de communication
sans fil à passer d'un faisceau de service à un faisceau cible, dans lequel l'un des
faisceaux candidats est sélectionné comme faisceau cible sur la base du rapport transmis.
2. Procédé selon la revendication 1, comprenant en outre la détection (310) d'une qualité
de signal décroissante, et dans lequel au moins la cause de la réservation de ressources
de liaison montante est effectuée en réponse à la détection de la qualité de signal
décroissante.
3. Procédé selon l'une quelconque des revendications 1 à 2, dans lequel au moins la cause
de la réservation de ressources de liaison montante est effectuée en réponse à la
détection (310) d'un échec d'une procédure de mobilité.
4. Procédé selon l'une quelconque des revendications 1 à 3, comprenant en outre la provocation
de (350) la transmission d'une indication concernant la réservation de ressources
de liaison montante au dispositif de communication sans fil.
5. Procédé selon l'une quelconque des revendications 1 à 4, dans lequel la sélection
de l'un des faisceaux candidats en tant que faisceau cible comprend la sélection de
l'un des faisceaux candidats sur lesquels le rapport est transmis dans la ressource
de liaison montante réservée.
6. Procédé selon l'une quelconque des revendications 1 à 5, dans lequel, pour un faisceau
candidat supporté par le nœud de réseau,
la transmission du signal de référence sur le faisceau candidat comprend la transmission
du signal de référence ; et
la provocation de la réservation de la ressource de liaison montante sur les faisceaux
candidats comprend la réservation de la ressource de liaison montante.
7. Procédé selon l'une quelconque des revendications 1 à 6, dans lequel, pour un faisceau
candidat supporté par un autre nœud de réseau supportant un faisceau candidat,
la provocation de la transmission du signal de référence sur le faisceau candidat
comprend la transmission d'une demande de signal de référence au nœud de réseau supportant
le faisceau candidat ; et
la provocation de la réservation de la ressource de liaison montante sur les faisceaux
candidats comprend la transmission d'une demande de ressource de liaison montante
au nœud de réseau supportant le faisceau candidat.
8. Procédé selon l'une quelconque des revendications 1 à 7, dans lequel la provocation
de la communication avec le dispositif de communication sans fil à utiliser un faisceau
cible comprend la transmission d'une commande de commutation de faisceau au dispositif
de communication sans fil.
9. Procédé pour un dispositif de communication sans fil (240) adapté pour communiquer
avec un nœud de réseau (120, 200) d'un réseau de communication cellulaire, dans lequel
le nœud de réseau et au moins certains autres nœuds de réseau du réseau de communication
cellulaire sont chacun adaptés pour prendre en charge une pluralité de faisceaux d'un
schéma de formation de faisceaux de signaux et pour communiquer avec le dispositif
de communication sans fil en utilisant au moins l'un de la pluralité de faisceaux,
le procédé comprenant :
effectuer des mesures (206) des signaux de référence (231, 232) reçus sur chacun d'un
ou plusieurs faisceaux candidats identifiés (111, 112) pour un commutateur de faisceaux,
dans lequel au moins l'un des un ou plusieurs faisceaux candidats identifiés a une
ressource de liaison montante réservée pour transmettre un rapport du dispositif de
communication sans fil ; et
transmettre le rapport (235) dans l'une des ressources de liaison montante réservées,
où le rapport est indicatif d'un résultat des mesures, où le rapport est pour la sélection
de l'un des faisceaux candidats comme faisceau cible, et où le faisceau cible est
pour une utilisation en communication avec le réseau de communication cellulaire.
10. Procédé selon la revendication 9, comprenant en outre la réception d'une indication
concernant la réservation de ressources de liaison montante depuis le réseau de communication
cellulaire.
11. Procédé selon l'une quelconque des revendications 9 à 10, dans lequel le rapport est
transmis dans la ressource de liaison montante réservée d'un faisceau candidat à sélectionner
comme faisceau cible.
12. Produit de programme informatique comprenant un support lisible par ordinateur (600),
ayant sur celui-ci un programme informatique comprenant des instructions de programme,
le programme informatique pouvant être chargé dans une unité de traitement de données
et adapté pour provoquer l'exécution du procédé selon l'une quelconque des revendications
1 à 11 lorsque le programme informatique est exécuté par l'unité de traitement de
données.
13. Agencement pour un nœud de réseau d'un réseau de communication cellulaire, dans lequel
le nœud de réseau et au moins certains autres nœuds de réseau du réseau de communication
cellulaire sont chacun adaptés pour supporter une pluralité de faisceaux d'un schéma
de formation de faisceau de signaux et pour communiquer avec un dispositif de communication
sans fil utilisant au moins l'un de la pluralité de faisceaux, l'agencement comprenant
un contrôleur (400, 500) adapté pour provoquer :
l'identification d'un ou plusieurs faisceaux candidats pour un commutateur de faisceaux,
en réponse à la détection de l'échec d'une procédure de mobilité ;
la transmission d'un signal de référence sur chacun des faisceaux candidats ;
la réservation d'une ressource de liaison montante d'au moins un des faisceaux candidats,
où les ressources de liaison montante sont destinées pour transmettre un rapport du
dispositif de communication sans fil, et où le rapport est indicatif d'un résultat
de mesures des signaux de référence ; et
la communication avec le dispositif de communication sans fil pour passer d'un faisceau
de service à un faisceau cible, dans lequel l'un des faisceaux candidats est sélectionné
comme faisceau cible sur la base du rapport transmis.
14. Agencement selon la revendication 13, dans lequel le contrôleur est en outre adapté
pour provoquer la détection d'une qualité de signal décroissante, et dans lequel au
moins la cause de la réservation des ressources de liaison montante est effectuée
en réponse à la détection de la qualité de signal décroissante.
15. Agencement selon l'une quelconque des revendications 13 à 14, dans lequel au moins
la cause de la réservation des ressources de liaison montante est effectuée en réponse
à la détection par le contrôleur d'un échec d'une procédure de mobilité.
16. Agencement selon l'une quelconque des revendications 13 à 15, dans lequel le contrôleur
est en outre adapté pour provoquer la transmission d'une indication concernant la
réservation de ressources de liaison montante au dispositif de communication sans
fil.
17. Agencement selon l'une quelconque des revendications 13 à 16, dans lequel la sélection
de l'un des faisceaux candidats comme faisceau cible comprend la sélection de l'un
des faisceaux candidats sur lesquels le rapport est acheminé dans la ressource de
liaison montante réservée.
18. Agencement selon l'une quelconque des revendications 13 à 17, dans lequel, pour un
faisceau candidat supporté par le nœud de réseau,
la transmission du signal de référence sur le faisceau candidat comprend la transmission
du signal de référence ; et
la provocation de la réservation de la ressource de liaison montante sur les faisceaux
candidats comprend la réservation de la ressource de liaison montante.
19. Agencement selon l'une quelconque des revendications 13 à 18, dans lequel, pour un
faisceau candidat supporté par un autre nœud de réseau supportant un faisceau candidat,
la provocation de la transmission du signal de référence sur le faisceau candidat,
comprend la transmission d'une demande de signal de référence au nœud de réseau supportant
le faisceau candidat ; et
la provocation de la réservation de la ressource de liaison montante sur les faisceaux
candidats comprend la transmission d'une demande de ressource de liaison montante
au nœud de réseau supportant le faisceau candidat.
20. Nœud de réseau d'un réseau de communication cellulaire comprenant l'agencement selon
l'une quelconque des revendications 13 à 19.
21. Agencement pour un dispositif de communication sans fil adapté pour communiquer avec
un nœud de réseau d'un réseau de communication cellulaire, dans lequel le nœud de
réseau et au moins certains autres nœuds de réseau du réseau de communication cellulaire
sont chacun adaptés pour supporter une pluralité de faisceaux d'un schéma de formation
de faisceau de signaux et pour communiquer avec le dispositif de communication sans
fil en utilisant au moins l'un de la pluralité de faisceaux, l'agencement comprenant
un contrôleur (400) adapté pour provoquer :
la réalisation de mesures de signaux de référence reçus sur chacun d'un ou plusieurs
candidats identifiés pour un commutateur de faisceau, dans lequel au moins l'un des
un ou plusieurs faisceaux candidats identifiés a une ressource de liaison montante
réservée pour transmettre un rapport depuis le dispositif de communication sans fil
; et
la transmission du rapport dans l'une des ressources de liaison montante réservée,
où le rapport est indicatif d'un résultat des mesures, où le rapport est destiné pour
la sélection de l'un des faisceaux candidats comme faisceau cible, et où le faisceau
cible est destiné à être utilisé en communication avec le réseau de communication
cellulaire.
22. Agencement selon la revendication 21, dans lequel le contrôleur est en outre adapté
pour provoquer la réception d'une indication concernant la réservation de ressources
de liaison montante depuis le réseau de communication cellulaire.
23. Agencement selon l'une quelconque des revendications 21 à 22, dans lequel le contrôleur
est adapté pour provoquer la transmission du rapport dans la ressource de liaison
montante réservée d'un faisceau candidat à sélectionner comme faisceau cible.
24. Dispositif de communication sans fil comprenant l'agencement selon l'une quelconque
des revendications 21 à 23.